Research on saving electrical energy has been conducted according to an energy saving policy. Particularly, for electrical products, a technology for cutting power supply to products when a user does not use it for a long time has been developed.
In addition, irrespective of a user's control, when a specific condition is satisfied such as there is no person for a predetermined time at a specific position, an automatic on/off switch for cutting the power supply to an electrical apparatus has been developed.
A sensor for detecting a person such as a passive pyroelectric infrared (PIR) sensor and an active microwave sensor may be used in the above case. The switch connected to a load is automatically closed when the sensor detects a person, and thereby power is supplied to the load. However, when a person is not detected by the sensor, the switch automatically opens, and thereby the power supplied to the load is cut.
The automatic on/off switch based on these technologies has advantages of electrical energy savings as well as eliminating the inconvenience of having to manually turn a switch on/off.
For theses reasons, fields to which the automatic on/off switch is applied gradually have increased. For example, the automatic on/off switch is may be used in a field of lighting industry, a field of alarm industry, a field in which electrical energy savings is required due to power consumption, a field of electric home appliances, and others.
Although there are many advantages in using the automatic on/off switch, in fact, there are few fields using it because of problems such as malfunctions of the sensor. More specifically, an active microwave sensor as the sensor for detecting has narrow coverage and further detects all objects that move in the coverage area, thereby causing an unnecessary on/off operation.
Also, since the passive PIR sensor reacts to infrared light from all living things, there are problems such as unnecessary on/off operation of the switch due to a dog or cat, light input from the outside, or heat change.
Further, although a person passes by around where the sensor for detecting is operated, without intent to operate an electric product, the switch is automatically turned on, thereby operating the electric product. Therefore, it is impossible to control the on/off operation of the switch within the coverage area of the sensor.
Additional apparatuses for solving the problems have been developed, but they raise the unit cost in producing the switch. Further, since the problems have not yet been completely solved, the additional apparatuses are not substantially used.
Accordingly, in fact, there are no fields in which the automatic on/off switch is used other than fields using lighting that is installed at an entrance and stairs, an alarm, an automatic door, and others.
As a related art to the automatic on/off switch, there is a saving switch that is disclosed in Korean Patent Issue No. 10-454532. In the saving switch, a corresponding light is manually turned on by a user such as by pressing an auto switch button or a manual switch button. At the same time, a sensor becomes turned off for a predetermined time, so the sensor cannot detect a user when the user enters within the coverage of the sensor. Meanwhile, when the sensor detects a user going out, the light is automatically turned off, or a predetermined sound is output to make the user turn off the light.
However, the switch does not operate when many people are within the coverage area. Also, in this case, although one person goes out of the coverage area, if another person remains there, the switch is turned off. In addition, when the lighting is on, it is automatically turned off only by operating the auto switch button while the lighting is manually turned off by a user if operating the manual switch button.
Accordingly, when a user goes out the coverage area after operating the manual switch button because of mistaking the manual switch button for the auto switch button, the lighting maintains the state of being turned on, thereby increasing the power consumption of the lighting.
As another related art to the automatic on/off switch, there a saving switch having an automatic mode function and a control method thereof which is disclosed in Korean Patent Publication No. 2005-0103121. The related art provides a saving switch that automatically causes lighting to be turned on when a sensor detects a moving object or opening of a door. After this, the saving switch automatically causes the light to be turned off when the sensor again detects a moving object or opening of a door.
The saving switch of No. 2005-0103121 has additional auto on/off functions in comparison with the saving switch of No. 10-454532. Thus, the saving switch of No. 2005-0103121 still has problems related to the saving switch of No. 10-454532 as well as problems that the light becomes unnecessary iteratively turned on/off by malfunction of the sensor.
The above information disclosed in this Background section is only for enhancement of understanding of the background of the invention and therefore it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art.